As a user of the search UI I may find confusing to see mixed kind of metadata shown in the search results
I don't think this qualifies as "use case". Some users may be confused by some things but this is not something that is formulated as use case. The use case would be something like "as a search UI user, I want all my search results have the same metadata" - but then I'd question why one would want that. Maybe "as a search UI user, I want search results to be easily comprehensible and provide enough information about the results" - but it feels underspecified.